Encapsulated motor compressor for refrigerating machines



June 15, 1965 P.A.BACHMANN 3,189,256

ENCAPSULATED MOTOR COMPRESSOR FOR REFRIGERA'I'ING HAQHINES Filed April2, 1965 United States Patent 1 O 7 Claims. 61. 230-58) The inventionrelates to an encapsulated motor compressor for refrigerating machinesof the type having a horizontally-disposed shaft and a cylinder headoverhanging the cross-sectional plane of the motor compressor.

Prior capsules have been constructed of a sufliciently large size, thatit has not been necessary to take any special precautions with respectto the protruding cylinder head. Similarly, the disposition of asufiicient amount of oil did not cause problems because of the largesize of the capsule. It is desirable, however, to have the capsule assmall as possible.

It is accordingly an object of the invention to reduce the size of thecapsule but at the same time providing sufficient space for the oilwithout increasing the oil level to any significant extent.

According to the invention, the motor compressor is closely enclosed bya capsule and the capsule is provided with an enlargement adapted toreceive. the cylinder head, the motor compressor being enclosed in thecapsule in such manner that the centerline of the cylinder is turneddownwards so that the enlargement is at least partly filled with the oilcontained in the capsule. i The size of the capsule may be significantlyreduced when its main body is constructed, as it is according to theinvention, independently of the protruding cylinder head. However, thisreduction of size also tends to cause the level of the oil to increaseand, as the quantity of oil for a certain system is provided within verynarrow limits, the oil will tend to rise to a level which may, forexample, be above the airgap of the electromotor. However, if theenlargement of the capsule, according to the invention, is utilized as apart of the oil sump, then a satisfactory low oil level and a reductionin the size .of the capsule can be eifectively combined.

According to a preferredembodiment of the invention, the wall of thecapsule extends with a vault directly into the enlargement and the extraspace thus defined is at least partly filled with oil. In the samemanner, the enlargement of the capsule as a projection of the cylinderhead can be vaulted and serve the same purpose. Since the enlargement isfor the most part filled by the cylinder head itself, it is preferableto enlarge the space which is available for the oil sump in the samemanner since the space thus provided is obtained without the externalsize of the entire capsule, including the enlargement, exceeding thedesired predetermined size.

It is particularly advantageous for the centerline of the cylinder to bedisposed with respect to the vertical centerline at an angle of about4545". With such a disposition, a great part of the cylinder head isturned away from the oil, which means a lesser displacement of the oil,which further contributes to, a lowering of the oil level. Furthermore,this aligning of the centerline or axis of the cylinder has theadvantage that the vaulted enlargement in the projection of the cylinderhead does not extend the exterior dimension of the entire capsule andthe vaulted continuation of the capsule extends it only to a very smallextent. Furthermore, oil for lubricating purposes during the startingperiod of the machine can be accumulated in the bottom of the cylinderduring the resting period of the machine. More- 3,189,256 Patented June15, 1965 over, the gas pressure in the working chamber of the cylindercan be relieved without counter pressure from the oil along the uppersurface of the cylinder, in contrast to an embodiment having avertically-hanging cylinder. The angle of 45 with respect to thevertical centerline offers the best conditions with respect to externalsize, but an angle of 55 offers a better lowering of the oil level.

According to another advantageous embodiment of the invention, part ofthe silencing chamber, which borders the cylinder, dips into the oil.This extra displacing of the oil can be accepted due to the foregoingconsiderations. A silencer cooled by oil has the advantage that thesucked-in gas, which first has cooled the entire machine, will pass intothe compressor with a lower temperature, thus increasing the efiiciencyof the compressor. In this connection it is of great importance that theopenings of the interconnecting channelsbetween the silencers can belocated above oil level. Due to these factors, which also are related tothe lowering ofthe oil level, gaskets can be eliminated between thecharmbers of the silencers and the closing plates without danger thatoil will be sucked in by the compressor and circulated in therefrigerating system and create noisy conditions. i

For motor compressors which have such a closely fitted encapsulation,normal helical spring mounting will only be usable to a limited extent.It is preferred to mount the motor compressor in horizontally-disposedspring pins. In this connection, the cylinder should be tilted to anextent with respect to the horizontal that it lies below one spring pin,i.e. two oppositely-located spring pins lie in the centerline of themotor compressor.

Further objects, features and characteristics of the invention will bereadily apparent from the following detailed description of anillustrative embodiment taken in connection with the single figure ofthe accompanying drawing in which is shown a cross-sectional view of acapsule containing a motor compressor seen from above.

The motor compressor illustrated in the drawing includes a motor body 1and has a substantially circular cross-section. The cylinderhead 2extends beyond, i.e. overhangsjf this cross-section to a limited extent,and the cylinder head consists, as usual, of a valve plate and a valvecover. The expression "cylinder head as used herein does not onlyinclude the parts mentioned, but also includes part of the cylinder tothe extent this part overhangs the cross-section of the motor compressorbody. The cylinder body 3 is molded or cast as a one-piece body integralwith the supporting element for the motor 1, the bearing for the motor,and both pressure silencers 6 and 7. In the same integral casting arealso found the connecting channels 8, 9, 10 and 11 connecting twosilencing chambers viz. a silencing chamber and the valve-chamber in thecylinder head 2. The entire unit is closed on the frontside by a cover12, which also includes a second bearing 13 for the motor crankshaft 14,and an inlet opening 15 to the suction silencer, and an opening 16leading to the pressure silencer. The screws which fasten the cover andthe other parts of compressor, in order to simplify the illustration ofthe invention, are not shown. The entire motor compressor is mounted inthe capsule by means of spring pins 18, said pins being disposed incorresponding grooves 19.

The capsule 17 encloses the motor compressor as closely as its contourpermits, i.e. it follows the circular outline of the motor compressoralong a very large part of both the crosswise and lengthwise section.Only in the area of the cylinder head 2 is an enlargement 20 of thecapsule provided. The centerline 21 of the cylinder tilts downwards tosuch an extent that the enlargement at least partly is filled with oil22, thus lowering the oil level 23 as much as possible.

In the basic construction of the invention, the capsule also enclosesthe cylinder head 2 very closely, as shown by the dotted line 24. Byreason of the downwardly-directed cylinder disposition, the space 25around .the cylinder head is also available for oil, in contrast to aconstruction with an upwardly-pointed cylinder disposition.

However, preferably, the wall of the capsule continues into a vault 26,which continues into the enlargement 20 of the capsule. In this manner,an extra space 27 for the oil is obtained without significantlyincreasing the crosswise and lengthwise dimensions of the capsule.

.It is not necessary to make the vault 26 in the plane .value a, in thiscase 55, the vault 28 does not affect the vertical and crosswiseexternal size of the capsule. Furthermore, the cylinder head 2 dips intothe oil 22 with only a fraction of its entire volume, which furtherdecreases the oil level 23. In addition, the oil, which is fed forcylinder lubrication, can be collected during the rest period of themachine along the downwardly-pointed surface U of the cylinder 3. Incontrast, the pressure in the working chamber of the cylinder 3 can berelieved along the upper surface of the cylinder without anycounterpressure from the oil.

From the drawing it is clear that the silencing chamber 4 bordering thecylinder partly also dips into the oil sump 22. As the oil has a lowertemperature than the sucked in gas stream, which heretofore has beenutilized to cool down the entire motor compressor, it is possible toemit some heat from the sucked in gas stream, thus increasing theefliciency of the compressor. The heat is relatively rapidly transmittedfrom the oil through the capsule to the ambient areas. With theconstruction described, it is possible to keep the oil level 23 of theoil sump below the openings of the channels 8 and 9 in the associatedsilencers. It is insured that the compressor cannot suck-in oil even ifthe oil has entered a silencer. Thus, the demands on the gaskets of thesuction silencers can be reduced and the gaskets between the cover 12and the component 1 forming the suction silencers can be eliminated.

It will be understood that the embodiment shown can be altered andmodified by those skilled in the art without departing from the scope ofthe invention as defined in the appended claims. Thus, the silencerchamber, for example, can be formed together with the cylinder as aone-piece component with the silencers closed at the front while theopen side of the silencers can be closed by the motor-supporting body.The invention also includes a construction with only one bearing for themotor crankshaft. The invention thus consists broadly in the capsuleenlargement for the cylinder head and the location thereof, especiallyin the case of motor compressors with a closely-enclosing capsule. Itwill be understood that the motor compressor per se can be of knownconstruction.

I claim:

1. An encapsulated motor compressor for refrigerating machinescomprising a capsule containing oil and a motor compressor having ahorizontally-disposed shaft and a cylinder head extending beyond thecross-section of the remainder of the motor compressor, said capsuleenclosing the motor compressor closely throughout and having a crosssection substantially circular along at least one half the cross sectionand an enlargement in cross section being provided to receive thecylinder head, the centerline of the cylinder being inclined downwardlyrelative to the horizontal to an extent that the enlargement provides anoil sump which is at least partly filled in operation with oil containedin said capsule.

2. A motor compressor according to claim 1, wherein the wall of thecapsule continues into the enlargement with a vault and the additionalspace thereby provided is at least partly filled with the oil.

3. A motor compressor according to claim 2, wherein the enlargement inthe projection of the cylinder head is also vaulted and the additionalspace thus provided is at least partly filled with the oil.

4. A motor compressor according to claim 1, wherein the centerline ofthe cylinder with respect to the vertical centerline is disposed at anangle of 4555.

5. A motor compressor according to claim 1, comprising means defining asuction silencer bordering the cylinder and extending into the oil sump.

6. A motor compressor according to claim 5, wherein said means definingsaid suction silencer defines a second suction silencer andinterconnecting channels with openings into the silencers, the openingsof the interconnecting channels of the suction silencers being disposedin operation above the oil level in said capsule.

7. A motor compressor according to claim 1, includinghorizontally-disposed spring pins mounting said motor compressor in saidcapsule, and the cylinder being tilted with respect to the horizontalcenterline and disposed below one of the spring pins.

References Cited by the Examiner UNITED STATES PATENTS 3/29 Crane 230581/38 McCune 23058

1. AN ENCAPSULATED MOTOR COMPRESSOR FOR REFRIGERATING MACHINESCOMPRISING A CAPSULE CONTAINING OIL AND A MOTOR COMPRESSOR HAVING AHORIZONTALLLY-DISPOSED SHAFT AND A CYLINDER HEAD EXTENDING BEYOND THECROSS-SECTION OF THE REMAINDER OF THE MOTOR COMPRESSOR, SAID CAPSULEENCLOSING THE MOTOR COMPRESSOR CLOSELY THROUGHOUT AND HAVING A CROSSSECTION SUBSTANTIALLY CIRCULAR ALONG AT LEAST ONE HALF THE CROSS SECTIONAND AN ELERGEMENT IN CROSS SECTION BEING PROVIDED TO RECEIVE THECYLINDER HEAD, THE CENTERLINE OF THE CYLINDER BEING INCLINED DOWNWARDLYRELATIVE TO THE HORIZONTAL TO AN EXTENT THAT THE ENLARGEMENT PROVIDES ANOIL SIMP WHICH IS AT LEAST PARTLY FILLED IN OPERATIVE WITH OIL CONTAINEDIN SAID CAPSULE.